**Siméon Denis Poisson **He was a French engineer and mathematician, famous for his equations. He was born in Pithiviers on June 21, 1781. He died in Paris on April 25, 1840. The son of a public administrator, he joined the *Ecole Polytechnique* in 1798, in Palaiseau, where he graduated, studying with teachers such as Lagrange, Laplace and Fourier, of whom he became a personal friend.

Poisson was considered Laplace's successor in the study of celestial mechanics and the attraction of spheroids. He also developed the Poisson Exponent, which is used in adiabatic transformation of a gas. This exponent is the ratio between the molar thermal capacity of a gas at constant pressure and the molar thermal capacity of a gas at constant volume. The law of adiabatic transformation of a gas says that the product between the pressure of a gas and its volume raised to the Poisson exponent is constant.

He also contributed to the theories of electricity and magnetism and studied the motion of the moon. Developed research on mechanics, electricity (Poison's constant), elasticity (Poison's ratio), heat, sound and mathematical studies (Poison integral in potential theory and Poison's bracket in differential equations) with application in medicine and astronomy. . He also produced writings on wave movements in general and contraction coefficients and the relationship between these and extension.

In 1812, he published works that helped electricity and magnetism become a branch of mathematical physics. In hydrodynamics, his most notable work was *Mémoire sur les équations générales de l'Equilibre et du mouvement des solves corps élastiques et des fluides* (1829), relating equilibrium of elastic solids and compressible fluid streams. Published the important treaty *Traité de mecanique* (1833), in two volumes. In *Recovering the Probability of the Matches *(1837), appeared the famous distribution of Poison, widely applied in statistics. In probability theory, he discovered the limited form of the binomial distribution, which later received its name. Currently the Poisson method is a random process of fundamental importance.